The present invention relates to improved method for producing a golf club head, and more particularly related to improvement in production of a wood-type golf club head having an FRP (fiber reinforced plastics) shell.
In one conventional method for producing such a golf club head, fibers impregnated with thermosetting synthetic resin are hardened halfway to form a crude FRP shell which is then shaped into a desired configuration. In this case, short fibers of about 1 mm length are used for reinforcement. Use of such short fibers in the shell, however, rather lowers the surface strength of the product.
In another conventional method, short fibers are kneaded with thermoplastic synthetic resin to form a crude mixture which is then subjected to injection shaping. In this case again, use of short fibers lowers strength of the product despite its easy processing.
In the other conventional method, a crude core is placed in position within the cavity of a mold while leaving a space between the crude core and the cavity wall and crude FRP shell is infused under pressure into the space. In this case, infusion pressure of the crude FRP shell tends to drive the crude core out of its initially set position, thereby disturbing the balance of weight of the product. Though various expedients are proposed to remove such ill influence of the infusion pressure, they in most cases have ill side effects such as scars on the surface of the product.
Aside from the problems of surface strength and balance of weight, general use of carbon fibers for reinforcement in the conventional art blackens the surface of the product and increases thermal adsorption during use, both being unwelcome from the view points of commercial value and function stability.